from django.contrib.auth.models import User
from django.contrib.auth import authenticate
from django.contrib.sites.models import Site
from django.template import Context, loader
from django import forms
from django.utils.translation import ugettext_lazy as _

class UserCreationForm(forms.ModelForm):
    """
    A form that creates a user, with no privileges, from the given username and password.
    """
    username = forms.RegexField(label=_("Username"), max_length=30, regex=r'^\w+$',
        help_text = _("Required. 30 characters or fewer. Alphanumeric characters only (letters, digits and underscores)."),
        error_message = _("This value must contain only letters, numbers and underscores."))
    password1 = forms.CharField(label=_("Password"), max_length=60, widget=forms.PasswordInput)
    password2 = forms.CharField(label=_("Password confirmation"), max_length=60, widget=forms.PasswordInput)
    
    class Meta:
        model = User
        fields = ("username",)
    
    def clean_username(self):
        username = self.cleaned_data["username"]
        try:
            User.objects.get(username=username)
        except User.DoesNotExist:
            return username
        raise forms.ValidationError(_("A user with that username already exists."))
    
    def clean_password2(self):
        password1 = self.cleaned_data["password1"]
        password2 = self.cleaned_data["password2"]
        if password1 != password2:
            raise forms.ValidationError(_("The two password fields didn't match."))
        return password2
    
    def save(self, commit=True):
        user = super(UserCreationForm, self).save(commit=False)
        user.set_password(self.cleaned_data["password1"])
        if commit:
            user.save()
        return user

class AuthenticationForm(forms.Form):
    """
    Base class for authenticating users. Extend this to get a form that accepts
    username/password logins.
    """
    username = forms.CharField(label=_("Username"), max_length=30)
    password = forms.CharField(label=_("Password"), max_length=30, widget=forms.PasswordInput)
    
    def __init__(self, request=None, *args, **kwargs):
        """
        If request is passed in, the form will validate that cookies are
        enabled. Note that the request (a HttpRequest object) must have set a
        cookie with the key TEST_COOKIE_NAME and value TEST_COOKIE_VALUE before
        running this validation.
        """
        self.request = request
        self.user_cache = None
        super(AuthenticationForm, self).__init__(*args, **kwargs)
    
    def clean(self):
        username = self.cleaned_data.get('username')
        password = self.cleaned_data.get('password')
        
        if username and password:
            self.user_cache = authenticate(username=username, password=password)
            if self.user_cache is None:
                raise forms.ValidationError(_("Please enter a correct username and password. Note that both fields are case-sensitive."))
            elif not self.user_cache.is_active:
                raise forms.ValidationError(_("This account is inactive."))
        
        # TODO: determine whether this should move to its own method.
        if self.request:
            if not self.request.session.test_cookie_worked():
                raise forms.ValidationError(_("Your Web browser doesn't appear to have cookies enabled. Cookies are required for logging in."))
        
        return self.cleaned_data
    
    def get_user_id(self):
        if self.user_cache:
            return self.user_cache.id
        return None
    
    def get_user(self):
        return self.user_cache

class PasswordResetForm(forms.Form):
    email = forms.EmailField(label=_("E-mail"), max_length=75)
    
    def clean_email(self):
        """
        Validates that a user exists with the given e-mail address.
        """
        email = self.cleaned_data["email"]
        self.users_cache = User.objects.filter(email__iexact=email)
        if len(self.users_cache) == 0:
            raise forms.ValidationError(_("That e-mail address doesn't have an associated user account. Are you sure you've registered?"))
    
    def save(self, domain_override=None, email_template_name='registration/password_reset_email.html'):
        """
        Calculates a new password randomly and sends it to the user.
        """
        from django.core.mail import send_mail
        for user in self.users_cache:
            new_pass = User.objects.make_random_password()
            user.set_password(new_pass)
            user.save()
            if not domain_override:
                current_site = Site.objects.get_current()
                site_name = current_site.name
                domain = current_site.domain
            else:
                site_name = domain = domain_override
            t = loader.get_template(email_template_name)
            c = {
                'new_password': new_pass,
                'email': user.email,
                'domain': domain,
                'site_name': site_name,
                'user': user,
            }
            send_mail(_("Password reset on %s") % site_name,
                t.render(Context(c)), None, [user.email])

class PasswordChangeForm(forms.Form):
    """
    A form that lets a user change his/her password.
    """
    old_password = forms.CharField(label=_("Old password"), max_length=30, widget=forms.PasswordInput)
    new_password1 = forms.CharField(label=_("New password"), max_length=30, widget=forms.PasswordInput)
    new_password2 = forms.CharField(label=_("New password confirmation"), max_length=30, widget=forms.PasswordInput)
    
    def __init__(self, user, *args, **kwargs):
        self.user = user
        super(PasswordChangeForm, self).__init__(*args, **kwargs)
    
    def clean_old_password(self):
        """
        Validates that the old_password field is correct.
        """
        old_password = self.cleaned_data["old_password"]
        if not self.user.check_password(old_password):
            raise forms.ValidationError(_("Your old password was entered incorrectly. Please enter it again."))
        return old_password
    
    def clean_new_password2(self):
        password1 = self.cleaned_data.get('new_password1')
        password2 = self.cleaned_data.get('new_password2')
        if password1 and password2:
            if password1 != password2:
                raise forms.ValidationError(_("The two password fields didn't match."))
        return password2
    
    def save(self, commit=True):
        self.user.set_password(self.cleaned_data['new_password1'])
        if commit:
            self.user.save()
        return self.user

class AdminPasswordChangeForm(forms.Form):
    """
    A form used to change the password of a user in the admin interface.
    """
    password1 = forms.CharField(label=_("Password"), max_length=60, widget=forms.PasswordInput)
    password2 = forms.CharField(label=_("Password (again)"), max_length=60, widget=forms.PasswordInput)
    
    def __init__(self, user, *args, **kwargs):
        self.user = user
        super(AdminPasswordChangeForm, self).__init__(*args, **kwargs)
    
    def clean_password2(self):
        password1 = self.cleaned_data.get('password1')
        password2 = self.cleaned_data.get('password2')
        if password1 and password2:
            if password1 != password2:
                raise forms.ValidationError(_("The two password fields didn't match."))
        return password2
    
    def save(self, commit=True):
        """
        Saves the new password.
        """
        self.user.set_password(self.cleaned_data["password1"])
        if commit:
            self.user.save()
        return self.user